In an earlier post, someone mentioned a trick you can show the jury regarding ping pong balls and HGN. What is this trick...I don't believe that I have ever seen it before.

Thanks
Stuart

I've heard pingpong balls rolling on sandpaper. As they wobble along, it mimics the inability of the eye to move smoothly.

I don't know if this qualifies as a trick but I drew an iris and pupil on a ping pong ball and made a hole in the bottom and attached it to a pencil with glue so the officer could rotate it on the witness stand as a demonstration for the jury. We did both the normal eye(smooth) and the drunk eye(jerky). Made sure we practiced it several times prior to the trial to get it right. Also can be done without the pencil inserted just using the hand only to rotate the ball. I Keep the "eye" in my desk for future trials and speeches to groups(Lion's club etc.) Seems to work well as an educational tool.